/*
 * @(#)ByteToCharDoubleByte.java	1.12 06/10/10
 *
 * Copyright  1990-2008 Sun Microsystems, Inc. All Rights Reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER
 * 
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version
 * 2 only, as published by the Free Software Foundation. 
 * 
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License version 2 for more details (a copy is
 * included at /legal/license.txt). 
 * 
 * You should have received a copy of the GNU General Public License
 * version 2 along with this work; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA 
 * 
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa
 * Clara, CA 95054 or visit www.sun.com if you need additional
 * information or have any questions. 
 *
 */

package	sun.io;

/**
 * @author Limin Shi
 *	   Sean Jiang
 */

public abstract class ByteToCharDoubleByte extends ByteToCharConverter {
    protected byte savedByte;
    /*
     * 1st level index, provided by subclass
     */
    protected short index1[];
    /*
     * 2nd level index, provided by subclass
     * every string has 0x10*(end-start+1) characters.
     */
    protected String  index2[];
    protected int start;
    protected int end;
    /*
     * Size of bad input that caused conversion to stop
     */
    protected int     badInputLength;
    public ByteToCharDoubleByte() {
        super();
        savedByte = 0;
    }
	   
    public int flush(char[] output, int outStart, int outEnd)
        throws MalformedInputException {
        if (savedByte != 0) {
            reset();
            badInputLength = 0;
            throw new MalformedInputException();
        }
        reset();
        return 0;
    }

    /**
     * Converts sequences of bytes to characters.
     * Conversions that result in Exceptions can be restarted by calling
     * convert again, with appropriately modified parameters.
     * @return the characters written to output.
     * @param input byte array containing text in Double/single Byte 
     * @param inStart offset in input array
     * @param inEnd offset of last byte to be converted
     * @param output character array to receive conversion result
     * @param outStart starting offset
     * @param outEnd offset of last byte to be written to
     * @throw UnsupportedCharacterException for any bytes 
     * that cannot be converted to the external character set.
     */
    public int convert(byte[] input, int inOff, int inEnd,
        char[] output, int outOff, int outEnd)
        throws UnknownCharacterException, MalformedInputException,
            ConversionBufferFullException {
        char	outputChar = REPLACE_CHAR;
        int     inputSize = 0;          // Size of input
        // Record beginning offsets
        charOff = outOff;
        byteOff = inOff;
        // Loop until we hit the end of the input
        while (byteOff < inEnd) {
            int byte1, byte2;
            if (savedByte == 0) {
                byte1 = input[byteOff];
                inputSize = 1;
            } else {
                byte1 = savedByte;
                savedByte = 0;
                inputSize = 0;
            }
            outputChar = convSingleByte(byte1);
            if (outputChar == REPLACE_CHAR) {	// DoubleByte char
                if (byteOff + inputSize >= inEnd) {
                    // split in the middle of a character
                    // save the first byte for next time around
                    savedByte = (byte) byte1;
                    byteOff += inputSize;
                    break;
                }
                byte1 &= 0xff;
                byte2 = input[byteOff + inputSize] & 0xff;
                inputSize++;
                outputChar = getUnicode(byte1, byte2);
            }
            if (outputChar == REPLACE_CHAR) {
                if (subMode)
                    outputChar = subChars[0];
                else {
                    badInputLength = inputSize;
                    throw new UnknownCharacterException();
                }
            }
            if (charOff >= outEnd)
                throw new ConversionBufferFullException();
            output[charOff++] = outputChar;
            byteOff += inputSize;
        }
        return charOff - outOff;
    }

    /**
     * Resets the converter.
     * Call this method to reset the converter to its initial state
     */
    public void reset() {
        byteOff = charOff = 0;
        savedByte = 0;
    }

    /*
     * Can be changed by subclass
     */
    protected char convSingleByte(int b) {
        if (b >= 0)
            return (char) b;
        return REPLACE_CHAR;
    }

    /*
     * Can be changed by subclass
     */
    protected char getUnicode(int byte1, int byte2) {
        if ((byte2 < start) || (byte2 > end))
            return REPLACE_CHAR;
        int n = (index1[byte1] & 0xf) * (end - start + 1) + (byte2 - start);
        return index2[index1[byte1] >> 4].charAt(n);
    }
    protected final static char REPLACE_CHAR = '\uFFFD';
}
